1. Technical Field of the Invention
2. Prior Art
This invention relates in a totally general sense to tires without an inner tube and, more particularly, concerns a device for their inflation.
Said tires without an inner tube, generally known as tubeless tires, have their beads suitably dimensioned and shaped, with the corresponding wheel rims presenting matching bead retention flanges with which said beads must necessarily make tight contact to form the seal.
Various systems are known for inflating such tires when locked on a usual tire removal machine, which is generally provided with a unit for supporting and locking the wheel (wheel rim+tire) in a bedded position, for example a self-centering unit.
A first known system comprises a hollow annular body provided with a circumferential series of orifices and connected to a compressed air source, and combined with a flexible hose, also connected to said source, to be coupled to the tire inflation valve.
To inflate the tire of said first known system, the lower bead (i.e. that facing the self-centering unit) must firstly be brought into contact with the respective wheel rim flange, after which the upper bead must be inserted into the channel of the wheel rim, flush with its seat.
Having done this the hollow annular body is disposed above the gap between the tire upper bead and the upper flange of the wheel rim, with the respective orifices orientated towards said gap; the flexible hose is connected to the inflation valve; and the two are fed with compressed air.
The simultaneous action of the two air flows creates a pressure pulse within the tire, with the result that the upper bead is urged into its seat in the wheel rim, after which the tire is inflated with the air fed through the inflation valve.
Said first known system has proved unsatisfactory because to operate on wheel rims of different nominal diameters correspondingly different hollow annular holed bodies are required, with all the ensuing problems.
In the second known system the jaws of the self-centering unit are provided with at least one through hole generally orientated towards its axis of rotation, and connected to a compressed air source via a valve.
In this case to inflate the tire, the upper tire bead must firstly be made to engage the respective wheel rim seat, then the lower side wall of the tire has to be raised to suitably distance the lower bead from its seat, after which the compressed air is fed in through the holes in the jaws.
By being suddenly fed into the tire through the gap created in this manner, the compressed air produces a pressure shock which causes the tire lower bead to tightly adhere to its seat in the wheel rim.
After said shock any intervention by the operator is obviously no longer necessary.
Said second known system has firstly proved uncomfortable because the operator has to maintain the tire raised, and is secondly generally complex and costly because it requires a rotary joint associated with the self-centering unit to enable the air to reach the jaws.
A third known system comprises two separate members disposed on one and the other side of the axis of the wheel locking unit, they being provided with respective air delivery apertures which face generally downwards and are each positioned on a manipulating and positioning unit provided with locking means.
Before proceeding to inflate a tire, its lower bead has to be engaged with the respective wheel rim seat, while the upper bead is at a distance from the respective flange of the wheel rim.
Having done this the operator positions said units such that said apertures are aligned with the annular gap existing between the wheel rim and the upper bead; he then locks the whole assembly in position and commands the arrival of the compressed air, which generally operates as already stated.
This third known system has also highlighted various problems, which can be summarized as follows.
Firstly it is generally bulky and complex because of the presence of said two separate members and the relative accessories.
Secondly the separate positioning of said two units and of their respective locking means involves relatively complex and lengthy operations.
Thirdly such a system can be dangerous should the operator omit to lock the component elements of the system in position.
This is because in such situations at least some of said elements, no longer retained due to said omission, can undergo untimely movement because of the sudden reaction thrust generated on opening the compressed air.
The main object of this invention is to provide means able to overcome the aforesaid problems.
Another object of the invention is to attain said main object within the context of a simple, rational, reliable and flexible construction which is of small overall size, of low cost and safe.
With regard in particular to said safety problem, according to the invention the device is structured such as to compel the operator to retain it in position during tire inflation, otherwise said inflation cannot proceed.
For this purpose the device of the invention comprises a movable implement generally shaped as a symmetrically deformable handlebar intended to be associated with a fixed part of a tire removal machine, and provided with at least two air delivery nozzles which can only be activated by the operator gripping the handlebar with both hands.
The device can be readily and easily manipulated and positioned both because of said handlebar shape and because it is suitably counterweighted to automatically assume its rest configuration when released.
Moreover, with regard to the flexibility of utilization of the invention, the aperture between the arms or handles of the handlebar can be advantageously adjusted readily by the operator in order to adapt it to the nominal diameter of the wheel rim.
These other characteristics of the invention, together with the constructional merits and details thereof, will be apparent from the ensuing detailed description given with reference to the figures of the accompanying drawings which illustrate a preferred embodiment thereof by way of non-limiting example.